Differentiation between Treatment-Induced Necrosis and Recurrent Tumors in Patients with Metastatic Brain Tumors: Comparison among 11C-Methionine-PET, FDG-PET, MR Permeability Imaging, and MRI-ADC-Preliminary Results.

BACKGROUND AND PURPOSE: In patients with metastatic brain tumors after gamma knife radiosurgery, the superiority of PET using 11C-methionine for differentiating radiation necrosis and recurrent tumors has been accepted. To evaluate the feasibility of MR permeability imaging, it was compared with PET using 11C-methionine, FDG-PET, and DWI for differentiating radiation necrosis from recurrent tumors. MATERIALS AND METHODS: The study analyzed 18 lesions from 15 patients with metastatic brain tumors who underwent gamma knife radiosurgery. Ten lesions were identified as recurrent tumors by an operation. In MR permeability imaging, the transfer constant between intra- and extravascular extracellular spaces (/minute), extravascular extracellular space, the transfer constant from the extravascular extracellular space to plasma (/minute), the initial area under the signal intensity-time curve, contrast-enhancement ratio, bolus arrival time (seconds), maximum slope of increase (millimole/second), and fractional plasma volume were calculated. ADC was also acquired. On both PET using 11C-methionine and FDG-PET, the ratio of the maximum standard uptake value of the lesion divided by the maximum standard uptake value of the symmetric site in the contralateral cerebral hemisphere was measured (11C-methionine ratio and FDG ratio, respectively). The receiver operating characteristic curve was used for analysis. RESULTS: The area under the receiver operating characteristic curve for differentiating radiation necrosis from recurrent tumors was the best for the 11C-methionine ratio (0.90) followed by the contrast-enhancement ratio (0.81), maximum slope of increase (millimole/second) (0.80), the initial area under the signal intensity-time curve (0.78), fractional plasma volume (0.76), bolus arrival time (seconds) (0.76), the transfer constant between intra- and extravascular extracellular spaces (/minute) (0.74), extravascular extracellular space (0.68), minimum ADC (0.60), the transfer constant from the extravascular extracellular space to plasma (/minute) (0.55), and the FDG-ratio (0.53). A significant difference in the 11C-methionine ratio (P < .01), contrast-enhancement ratio (P < .01), maximum slope of increase (millimole/second) (P < .05), and the initial area under the signal intensity-time curve (P < .05) was evident between radiation necrosis and recurrent tumor. CONCLUSIONS: The present study suggests that PET using 11C-methionine may be superior to MR permeability imaging, ADC, and FDG-PET for differentiating radiation necrosis from recurrent tumors after gamma knife radiosurgery for metastatic brain tumors.

PET findings of intramedullary tumors of the spinal cord using [18F] FDG and [11C] methionine.

BACKGROUND AND PURPOSE: Only a few reports on intramedullary tumors of the spinal cord using PET have been published. We report findings of PET by using [(18)F] fluorodeoxyglucose and [(11)C] methionine and discuss the usefulness of the findings in patients with intramedullary tumors of the spinal cord. MATERIALS AND METHODS: PET/CT was performed in 9 patients with intramedullary tumors of the spinal cord: Six had ependymomas, 1 had an anaplastic astrocytoma, 1 had a hemangioblastoma, and 1 had a cavernous angioma. The maximum standardized uptake value of the tumor was measured and compared with pathologic findings. RESULTS: The SUVmax of FDG and MET in a case of anaplastic astrocytoma was high. The SUVmax of FDG and MET was relatively high in 4 of 6 cases of ependymoma (excluding myxopapillary ependymomas). A case of hemangioblastoma showed decreased uptake of both FDG and MET (SUVmax = 2.0 and 1.4, respectively). Three cases with hemorrhage (1 case of ependymoma, 1 case of cellular ependymoma, and 1 case of cavernous angioma) showed a relatively increased uptake of FDG. CONCLUSIONS: Both FDG and MET accumulated to a large degree in an anaplastic astrocytoma and accumulated in ependymomas (excluding a myxopapillary ependymoma). FDG can accumulate in tumors with hemorrhage. More investigation of a larger number of patients is required to evaluate the diagnostic value of PET with FDG and MET for imaging intramedullary tumors of the spinal cord.

Contrast-enhanced multi-shot echo-planar FLAIR in the depiction of metastatic tumors of the brain: comparison with contrast-enhanced spin-echo T1-weighted imaging.

BACKGROUND: The usefulness of fast fluid-attenuated inversion-recovery (FLAIR) sequences after administration of contrast medium (f-FLAIR (+)) has been shown in depicting brain tumors including metastases and meningeal carcinomatosis. Contrast-enhanced multi-shot echo-planar FLAIR (Ms-EPI-FLAIR (+)), comprising combined sequences of f-FLAIR (+) and Ms-EPI, may provide the advantages of f-FLAIR (+) along with rapid acquisition. PURPOSE: To compare Ms-EPI-FLAIR (+) with post-contrast spin-echo T1-weighted imaging (SE-T1WI (+)) in the depiction of brain metastases. MATERIAL AND METHODS: In 14 patients with metastatic tumors of the brain, spin-echo precontrast T1-weighted imaging (SE-T1WI (-)), fast spin-echo T2-weighted imaging (FSE-T2WI), fast-FLAIR, SE-T1WI (+), and Ms-EPI-FLAIR (+) were acquired. For qualitative evaluation of SE-T1WI (+) and Ms-EPI-FLAIR (+), receiver operating characteristic (ROC) analysis was performed in two different readers. For quantitative analysis, the intensity ratios (intensity of tumor divided by intensity of peritumoral region) in SE-T1WI (+) and Ms-EPI-FLAIR (+) were compared. RESULTS: Although pre-contrast f-FLAIR detected 84 of 106 tumors, Ms-EPI-FLAIR (+) detected 98 of 106 tumors. In the ROC analysis for observers A and B, Az values in SE-T1WI (+) did not differ from values in Ms-EPI-FLAIR (+). Quantitatively, the intensity ratio in Ms-EPI-FLAIR (+) also did not differ from that in SE-T1WI (+). CONCLUSION: Detectability of brain metastases with Ms-EPI-FLAIR (+) is almost similar to that with SE-T1WI (+). Ms-EPI-FLAIR (+) could be an alternative to SE-T1WI (+) in the depiction of brain metastases.

Venous Anatomy of the Sphenoparietal Sinus: Evaluation by MR Imaging.

SUMMARY: The termination of the superficial middle cerebral vein (SMCV) has been described as entering or being partially equivalent to the venous sinus coursing under the lesser sphenoid wing, which has classically been called the sphenoparietal sinus. However, the recent literature reports that the SMCV is not connected to the sphenoparietal sinus. In this study, the venous anatomy was evaluated to clarify the anatomy of the sphenoparietal sinus and the termination of the SMCV. Magnetic resonance imaging (MRI) was performed on 1.5-T superconductive units using a three-dimensional fast spoiled gradientrecalled acquisition in the steady state (3-D fast SPGR) sequence with fat suppression in a total of 48 sides of 24 patients. Coronal source images and reconstructed axial images were displayed on the Advantage Window Console, and connections to the cavernous sinus were then evaluated for the venous sinus coursing under the lesser sphenoid wing (hereafter called the sinus of the lesser sphenoid wing), the middle meningeal vein, and the SMCV. The following findings were observed bilaterally in all patients. The sinus of the lesser sphenoid wing was connected medially with the cavernous sinus and laterally with the anterior branch of the middle meningeal vein near the pterion. The anterior branch of the middle meningeal vein entered the bony canal laterally above the junction with the sinus of the lesser sphenoid wing and coursed along the inner table of the skull or emerged into the diploic vein, indicating its parietal portion. Although the termination of the SMCV had several patterns, the SMCV was not connected with the sinus of the lesser sphenoid wing in any of the patients. The sphenoparietal sinus is considered to consist of the sinus of the lesser sphenoid wing and the parietal portion of the anterior branch of the middle meningeal vein; these were identified as venous structures distinct to the SMCV.

Balloon occlusion test of the internal carotid artery: correlation with stump pressure and 99mTc-HMPAO SPECT.

PURPOSE: To evaluate the correlation of stump pressure during balloon occlusion test and relative cerebral blood flow (relative CBF) as measured by 99mTc-hexamethylpropyleneamine oxime (99mTc-HMPAO) single-photon emission computed tomography (SPECT) after test occlusion. MATERIAL AND METHODS: Balloon occlusion test of the internal carotid artery (ICA) was performed in 25 patients. The count ratio of occluded hemisphere to non-occluded hemisphere was calculated on 99mTc-HMPAO SPECT. The ratio of mean stump pressure to mean arterial pressure during carotid occlusion during the balloon occlusion test was compared with the count ratio of 99mTc-HMPAO SPECT. RESULTS: Two patients failed to tolerate even brief carotid occlusion. The other 23 patients showed no ischemic deficit during occlusion of the ICA. In 13 of these 23 patients, the ratios of mean stump pressure to mean arterial pressure were more than 50%, and the count ratios on SPECT were more than 85%. In 10 of 23 patients, the ratios of mean stump pressure to mean arterial pressure were less than 50%, and the count ratios on SPECT were variable. CONCLUSION: Maintenance of a mean stump pressure of 50% or more of the mean systemic pressure during test occlusion indicates adequate cerebral blood flow during carotid occlusion.

Dural arteriovenous fistulas of the cavernous sinus with onset of intracerebral haemorrhage mimicking hypertensive putaminal hemorrhage.

We describe a patient with dural arteriovenous fistulas of the cavernous sinus (CS-dAVFs) who developed an intracerebral haemorrhage (ICH) mimicking hypertensive putaminal haemorrhage. Drainage into the superior ophthalmic vein (SOV) and inferior petrosal sinus (IPS) was not demonstrated on cerebral angiography, and only cortical venous reflux into the Sylvian vein was observed. In cases of venous drainage concentrated on the Sylvian vein, CS-dAVFs could indicate ICH with radiological appearance resembling putaminal haemorrhage.

Postoperative three-dimensional CT angiography after cerebral aneurysm clipping with titanium clips: detection with single detector CT. Comparison with intra-arterial digital subtraction angiography.

AIM: To assess the significance of three-dimensional computed tomography angiography (3D-CTA) in detecting remnant necks after cerebral aneurysm clipping. MATERIALS AND METHODS: A total of 59 patients (77 aneurysms) underwent surgery using titanium clips. Two blinded observers independently evaluated the presence of neck remnants on shaded-surface display (SSD) imaging, volume rendered (VR) imaging, and intra-arterial digital subtraction angiography (IADSA). RESULTS: Mean sensitivity and specificity for detecting neck remnants were 50.0 and 74.2% for SSD imaging, 61.5 and 82.8% for VR imaging, and 92.3 and 92.2% for IADSA, respectively. Receiver operating characteristic (ROC) analysis revealed excellent diagnostic performance for IADSA [mean area under ROC curve (Az)=0.97], and good diagnostic performance for 3D-CTA (Az=0.70 and 0.76 for SSD and VR, respectively). Specificity of VR was better than that SSD (p=0.082), however, there was no significant difference between them. CONCLUSION: Use of 3D-CTA techniques can facilitate postoperative evaluation.

Carotid-cavernous fistula associated with an intracranial lesion caused by cortical venous reflux.

SUMMARY: Digital subtraction angiography (DSA) and magnetic resonance imaging (MRI) findings in 20 patients with carotid-cavernous fistula (CCF; 3 direct CCFs and 17 indirect CCFs) were retrospectively reviewed to evaluate venous drainage patterns that may cause intracerebral haemorrhage or venous congestion of the brain parenchyma. We evaluated the relationship between cortical venous reflux and abnormal signal intensity of the brain parenchyma on MRI. Cortical venous reflux was identified on DSA in 12 of 20 patients (60.0%) into the superficial middle cerebral vein (SMCV; n=4), the uncal vein (n=2), the petrosal vein (n=2), the lateral mesencephalic vein (LMCV; n=1), the anterior pontomesencephalic vein (APMV; n=1), both the APMV and the petrosal vein (n=1) and both the uncal vein and the SMCV (n=1). Features of venous congestion, such as tortuous and engorged veins, focal staining and delayed appearance of the veins, were demonstrated along the region of cortical venous reflux in the venous phase of internal carotid or vertebral arteriography in six of 20 patients (30.0%). These findings were not observed in the eight CCF patients who did not demonstrate cortical venous reflux. MRI revealed abnormal signal intensity of the brain parenchyma along the region with cortical venous reflux in four of 20 indirect CCF patients (20%). Of these four patients, one presented with putaminal haemorrhage, while the other three presented with hyperintensity of the pons, the middle cerebellar peduncle or both on T2- weighted images, reflecting venous congestion. The venous drainage routes were obliterated except for cortical venous reflux in these four patients and the patients without abnormal signal intensity on MRI had other patent venous outlets in addition to cortical venous reflux. CCF is commonly associated with cortical venous reflux. The obliteration or stenosis of venous drainage routes causes a converging venous outflow that develops into cortical venous reflux and results in venous congestion of the brain parenchyma or intracerebral haemorrhage. Hyperintensity of brain parenchyma along the region of cortical venous reflux on T2-weighted images reflects venous congestion and is the crucial finding that indicates concentration of venous drainage into cortical venous reflux.

A primary retroperitoneal serous cystadenocarcinoma with clinically aggressive behavior.

CASE REPORT: We describe a 44-year-old woman with a primary retroperitoneal serous cystadenocarcinoma as the fourth report in the world literature. A contrast-enhanced computed tomographic scan of the abdomen demonstrated a mass with enhanced solid mural nodules and septa in the left retroperitoneum. Serum CA19-9 was elevated at 181 U/ml. The patient underwent a complete resection of the retroperitoneal tumor with a partial resection of the psoas major muscle and its fascia. Pathological examination showed a well-differentiated papillary serous cystadenocarcinoma of ovarian type and locoregional lymph node metastases. Seven months after surgery, the patient developed a pelvic recurrence, and underwent a total hysterectomy, a left salpingo-oophorectomy and a resection of the metastatic mesenteric mass. Two months after the second surgery, serum CA19-9 and CA125 increased to 1,114 U/ml and 218 U/ml, respectively. A solitary liver metastasis was confirmed on a computed tomographic scan. The patient is now being treated with weekly docetaxel and carboplatin. CONCLUSION: The present case illustrates the clinically aggressive nature of a primary retroperitoneal serous cystadenocarcinoma.

Transvenous embolization of dural arteriovenous fistula of the cavernous sinus. Fistulous points and route of catheterization.

SUMMARY: We reviewed magnetic resonance (MR) images and digital subtraction angiograms (DSA) from eight patients with dural arteriovenous fistula of the cavernous sinus (DAVFCS) to clarify the fistulous points and to evaluate the venous access routes into the cavernous sinus for transvenous embolization (TVE). Multiplanar reconstruction of the MR images was achieved using three-dimensional fast spoiled gradient-recalled acquisition in the steady state (3-D fast SPGR) after the intravenous administration of gadopentetate dimeglumine (Gd-DTPA). TVE was performed using microcoils via the inferior petrosal sinus (IPS) using the transfemoral approach in five patients, via the facial vein and superior ophthalmic vein (SOV) using the transfemoral approach in 1 patient, and by SOV puncture in two patients. Most fistulas were detected in the posterior portion of the cavernous sinus or in the posterior intercavernous sinus in all of the patients. Fistulas identified as hyperintense dots or lines on contrast-enhanced 3-D fast SPGR images and were replaced with the microcoils. Target embolization of the fistulas was feasible in three patients treated via the SOV and in one patient treated via the IPS. Contrast- enhanced 3-D fast SPGR can help to identify the fistulous points of DAVFCS. Precise identification of fistulous points and selection of the adequate access route are mandatory for efficient TVE of DAVFCS.

[A patient with Moyamoya-like vessels after radiation therapy for a tumor in the basal ganglia].

A patient with Moyamoya-like vessels after radiation therapy for treatment of a tumor in the basal ganglia is reported. He was diagnosed as Down syndrome at birth. He had a tumor in the left basal ganglionic region at 12 years of the age. The tumor increased in size at age 14. He underwent cerebral angiography, which did not show a stenosis nor occlusion of the internal carotid artery, anterior cerebral artery, nor the middle cerebral artery. He received radiation therapy with a total dose of 56 Gy. He presented a dressing apraxia at age 19. MRI showed cerebral infarction in the left temporo-occipital region. Right internal carotid angiography revealed a severe stenosis of the internal carotid artery and anterior cerebral artery as well as a severe stenosis of the middle cerebral artery on the right side. Moyamoya-like vessels were seen in the basal ganglionic region. Left internal carotid angiography also showed a stenosis of the internal carotid artery and anterior cerebral artery as well as a severe stenosis of the middle cerebral artery on the left side. Moyamoya-like vessels were seen in the basal ganglionic region. Leptomeningeal anastomose and transdural anastomose were bilaterally seen. These arterial occlusion and stenotic phenomenon corresponded to a previous radiation field. These Moyamoya-like vessels with arterial stenosis and occlusion were thought to be due to radiation-induced vasculopathy, because a previous cerebral angiography showed a normal caliber of cerebral arteries. This patient showed that patients with radiation therapy in their early childhood should be carefully observed considering the possibility of this phenomenon.

Dural arteriovenous fistula of the cavernous sinus with cortical venous reflux of the posterior fossa via a bridging vein.

We describe a patient who had a dural arteriovenous fistula of the cavernous sinus with cortical venous reflux into the lateral mesencephalic vein and cerebellar hemispheric veins via a bridging vein connected with the basilar plexus. The fistula and reflux disappeared after transvenous embolization using interlocking detachable coils.

Extradural neuromas at the petrous apex: report of two cases.

OBJECTIVE AND IMPORTANCE: Two rare cases of middle cranial fossa neuroma located in the epidural space at the petrous apex are reported. CLINICAL PRESENTATION: Two women, aged 58 and 49 years, were admitted to our hospital with diagnoses of cavernous sinus tumor. Analysis of preoperative computed tomography scans showed bone erosion of the petrous apex, and magnetic resonance imaging demonstrated the presence of an extradural mass located along the course of the petrous internal carotid artery in both patients. INTERVENTION: The tumor was completely removed in one patient and partially removed in the other by use of the epidural middle cranial fossa transpetrosal approach. In both patients, histological examination of tumor specimens revealed neuroma. CONCLUSION: Because surgical exploration revealed that these epidural tumors adhered tightly to the internal carotid artery, and because they had no relationship to the trigeminal nerve, facial nerve, or proximal greater superficial petrosal nerve, in our opinion, these tumors originated from the distal portion of the greater superficial petrosal nerve or the deep petrosal nerve. These neuromas were mainly found in a site under the cavernous sinus at the petrous apex, a location not previously reported.

Comparison of thallium-201 and gallium-67 imaging in evaluation of head and neck tumors.

PURPOSE: 201Tl imaging was compared with 67Ga imaging in the detection of malignant head and neck tumors. METHOD: Eighteen patients with tumors in the head and neck region underwent both planar and SPECT imaging using 201Tl-chloride and 67Ga-citrate. The detection of primary tumors and lymph node (LN) metastases by visual evaluation was compared between 201Tl and 67Ga imaging. Additionally, quantitative analysis of the SPECT images was performed in eight patients. RESULTS: On visual evaluation, primary tumor uptake was detectable in 100% on the 201Tl SPECT images compared with 44% on the 67Ga SPECT images. The sensitivity, specificity, and accuracy of 201Tl in detecting LN metastases were higher than those of 67Ga SPECT; however, there was no statistical difference between 201Tl and 67Ga. The tumor-to-background ratio was significantly higher on 201Tl SPECT than on 67Ga SPECT. CONCLUSION: This study suggested that 201Tl could be useful in the evaluation of malignant tumors in the head and neck region.

[Imaging of tumors of the spine and spinal cord].

Imaging of the spine and spinal cord has traditionally been accomplished with plain radiography, myelography, and CT. Recently, MR imaging has become the technique of choice in the assessment of lesions of the spine and spinal cord. MR imaging provides accurate localization of intramedullary, intradural extramedullary, and extradural tumors. Ependymomas and low-grade astrocytomas are the most common intramedullary tumors. MR imaging findings are distinguishable by the delineation and size of the lesion, and the signal intensity on T2-weighted images. Other less common tumors include malignant astrocytomas, hemangioblastomas, and intramedullary metastasis. Numerous foci of high-velocity signal loss are seen in the hemangioblastomas. Metastasis, meningiomas, and schwannomas are the most common intradural extramedullary tumors. Meningiomas are characterized by dural enhancement on postcontrast T1-weighted images. Schwannomas and neurofibromas often erode bony structures and appear to be dumbbell-shaped. Epidural metastasis accounts for the majority of extradural tumors. Primary malignant extradural tumors include lymphomas, chordomas, and so on. The most common primary benign extradural tumor is hemangioma, which often appears to be hyperintense on both T1-weighted and T2-weighted images. Intramedullary non-neoplastic lesions include demyelinating, vascular, and infectious diseases. Diffuse, peripheral, or speckled contrast enhancement, and lack of contrast enhancement may suggest non-neoplastic lesions.

Germ cell tumors of the central nervous system originating from non-pineal regions: CT and MR features.

CT and MR findings were retrospectively reviewed in 12 patients with germ cell tumors originating from the non-pineal regions. Cystic or necrotic components were seen in 6 patients. Of 4 germinomas, 2 showed mixed density on the CT. The MR signal intensity of the tumor was non-specific. Of 8 germinomas, 4 were inhomogeneously enhanced on postcontrast CT and T1-weighted MR images. CT and MR features of germinomas originating from non-pineal regions frequently differ from those of germinomas originating from the pineal region. The mass of the tumor often appeared cystic and inhomogeneously enhanced following contrast infusion.

High uptake of 123I-metaiodobenzylguanidine related to olfactory neuroblastoma revealed by single-photon emission CT.

We studied a case of olfactory neuroblastoma by noting 123I-metaiodobenzylguanidine (MIBG) uptake revealed by single-photon emission CT (SPECT). MR imaging revealed an enhancing tumor extending from the left nasal cavity to the bilateral anterior frontal cranial fossae. SPECT revealed high 123I-MIBG uptake in the enhancing tumor. SPECT-revealed 123I-MIBG uptake appears to be clinically useful for distinguishing olfactory neuroblastomas from other tumors, especially suprasellar meningiomas.

A case of moyamoya-like vessels combined with brain anomaly.

We report here a rare case of moyamoya-like vessels combined with brain anomaly. MR imaging revealed a small corpus callosum and stenosis of the internal carotid arteries. T2-weighted images revealed multiple hyperintense lesions in the cerebral deep white matter, suggesting ischemic or abnormal myelinated tissues. Cerebral angiography showed aplastic carotid siphons and anomalous aneurysmal dilatation of the petrous portion of the internal carotid arteries. The terminal portion of the internal carotid arteries and horizontal portion of the middle cerebral artery were stenotic with moyamoya-like vessels.

Comparison of MR imaging with CT in depiction of tumour extension into the pterygopalatine fossa.

The computed tomography (CT) and magnetic resonance imaging (MRI) results of 30 consecutive patients with tumours in the skull base, and who had abnormalities of the pterygopalatine fossa (PPF) on CT or MRI, were retrospectively compared with respect to visualization of tumour infiltration into the PPF. CT did not depict the abnormalities in the PPF in five patients (17%), while unenhanced T1-weighted MR images depicted tumour infiltration in all patients. Obliteration of PPF fat was better visualized on CT than T2-weighted and proton density weighted MR images, as were bony abnormalities. On MRI, intracranial extension was seen in eight of 25 patients with extracranial tumour. MRI is a sensitive method of demonstrating both tumour infiltration of the PPF and perineural tumour spread.